Computer automatic reset



J ly 1952 L. A. NETTLETON ET AL 2,605,450

COMPUTER AUTOMATIC RESET Tiled Jan. 7, 1946 2 SIIEETS-SHEET 2 FIG. 5

INVENTORS LEROY A. NETTLETON I HENRY S. OMMERSMR- ATTORNEY Patented July29, 1 952 2,605,450 COMPUTER- AUTOMATIC RESET Leroy A.NettletomBrookline, and Henry S. Sommers, Jr., Belmont, Mass.,assignors, by mesne assignments, tothe United States of America asrepresented'by the Secretary of the Navy Application'January 7, 1946',Serial No. 639,67

6 Clailris.

, 1 This" invention relates to synchros, and more particularly tosynchros used to position auxiliary apparatus.

.fSynchros are well knownin the art-,and are usually encountered in datatransmission systems. Whena driven element in'data transmissionapparatus must be reset at the conclusion of'some operation to onecertain position and held stationary at that point, mechanical powerfrom some source other than synchros is usually necessary. Generallythis source of power is a motor with associated gears or other drivingmechanisms which necessarily complicate many systems using synchros. v

Therefore the general object of the; present invention is to provide forthe utilization of a synchro, normally used for data transmission, as amotor to operate a driven element. I

It is a further object of the present invention to provide'means forswitching a synchro so that .it may function to transmitdata, to operateas a motor, orto lock a driven element.

'These and other objects will be apparent from the followingspecification when taken with the accompanying, drawings in which:

Fig; 1 is a schematic'diagram of an embodiment types of.synchro-unitsmay be used. Magnetic switch 1 [operates upon theenergization of magnet 24 whenswitch 23 is closed to connect the synchroto a data transmission circuit, and when switch 23 is openedthe synchroconnects to magnetic switch l2. Magnetic switch I2 is operated .bymagnet 25-and switch 22, the latterbeing controlled by cam l3. Switchesl I and [2, although shown for convenience as magnetic switches, may beany other suitable switching apparatus.

Transformer [4 when connected to a suitable alternating voltage supply,furnishes a voltage pattern at its secondary suitable for locking asynchro unit in a stationary position in a manner known to the art.

to a stator winding of the synchro motor through Capacitor I5 isconnected switch l6 which is operated bycam [1. The capacitor l5 causesthe synchro motor to operate as a two phase induction motor, the runningdirection being determined by the position of switch l6. Cams l3 and Ilare mechanically connected to the rotor of the synchro motor asindicated by dotted lines 18, I9, 20 and rotation reduction mechanism2|. Magnetic switches II and [2 are powered by a suitable supplyconnected at terminals 28 and 29. A single phase alternating voltagesupply, connected at terminals 26 and 21, and 26' and 21, furnishespower to synchro motor I0 and transformer M.

Fig. 2 illustrates a form of driven element mechanically connecting acam system, the latter comprising cams l3 and H, to synchro motor [0.Thus, synchro motor III has its rotorshaft 30 operati g a small gear 3|which turns large gear 32. Large gear 32 turns shaft 33 on which cams I3and I1 are mounted. These cams operate switches 22 and I6 respectively.Arrow 34 indicates a point on the periphery of large gear 32 whichcorresponds in position to the protrusion in cam l3. Arrow 35 is a pointadjacent to large gear 32 so determined that if arrows 34 and 35coincide, cam I3 operates switch 22. It may be further seen that switchIt is operated one way or the other by cam ll depending on whether arrow34 is in one or the other half region of large gear 32 as viewed in Fig.2.

Fig. 3 illustrates an alternative driven element and cam systemmechanically connecting synchromotor l0 and switches l6 and22. In thisfigure a single cam 40 replaces cam system [3, I! (Fig. 2). Cam 40,however, operates switches 16 and 22 in the same relation to large gear32 as was shown to occur in Fig. 2.

Fig. 4 is a simplified schematic diagram showing how a pattern ofvoltage isapplied tothe windings of synchro motor I0 to cause it to lockin a particular stationary position. Transformer I4 is shown withconventional primary and tapped secondary windings. However the synchromay be directly connected to the line voltage supply, or an autotransformer may be used to provide a different excitation level. Theprocess here shown is generally known in the art as locking atelectrical zero or zeroing. This operation is effected when theswitching elements of Fig. 1 are operated as will be described-below.

Fig. 5 shows in simplified form how the synchro I0 is made to operate asa two phase induction motor. Two stator coils are connected in seriesacross the single phase alternating voltage supply 26 and 21, and thethird stator-coil is connected to one side of the supply through seriescapacitor l5. This capacitor provides a shift in phase angle of thecurrent through the third stator coil, so that the resulting efiect istwo phase stator excitation. This phase shift may be accomplished by anyother impedance element, as for example, a resistor or inductor, as iswell understood. This two phase excitation produces a rotating magneticfield within the synchro, causing the rotor to revolve in the mannerwell known for induction motors. Changing the position of switch itreverses the direction of rotation because the time relations in themagnetic field are reversed. Induced currents in the laminated core ofthe synchros rotor act in the same manner as currents in the rotor of anordinary motor. Hence the synchros rotor may be short circuited, opencircuited, or closed through a resistance.

Referring again to Fig. 1, it Will be shown how the present inventionmay be used for data transmission, or as an apparatus for resetting andlooking a driven element at a predetermined point. When synchro motorii] is used for data transmission, it is connected by the switchingsystem shown to a data transmission circuit by means or magnetic switchit when the movable arms thereof are thrown upward as viewed in Fig. 1.Magnetic switch H thus electrically disconnects all other parts of thecircuit from the synchro motor.

When synchro motor is used to reset and lock a driven element (such asshown in Fig. 2 or 3) at a predetermined point, magnetic switch H isoperated to disconnect the synchro motor from the data transmissioncircuits, and to connect the synchro motor to magnetic switch l2. Thisoccurs when the movable switch arm of switch 1 I is thrown downward asviewed in Fig. 1. If switch 22 is not closed, switch [2 is in thedownward position. Cam I? and associated switch it then connectscapacitor Iii and the single phase alternating voltage supply at 26, 2?to synchro motor In through the contacts of switch 12, causing thesynchro motor to act as a two phase induction motor. The direction ofrotation of the synchro motor is determined by the position of switchIt, which in turn is determined by which side of cam 17 operates switchit. Being connected as a two phase motor, synchro motor It) operates thedriven element and the cam system in one direction or the other untilthe protrusion on cam 13 operates switch 22. Switch 22 then operatesmagnetic switch l2 and throws the movable arms thereof upward as viewedin Fig. i. This disconnects the synchro motor from capacitor 55 and thesingle phase supply, terminals 26 and 2?, and connects the synchro motorto transformer I l which furnishes a voltage pattern which looks thesynchro motor in a single stationary position, as previously describedin connection with the simplified zeroing circuit, Fig. 4.

Since changes may be made in th system described, and difierentembodiments of the Present invention may be made without departin fromthe scope thereof, it is intended that all matter contained in the abovedescription or shown in the accompanying drawings shall be interpretedin an illustrative and not limiting sense, and therefore that theinvention is to be limited only by the prior art and the spirit of thappended claims.

What is claimed is:

1. A synchro system comprising a synchro motor, a driven elementmechanically connected to said synchro motor, a cam system mechanicallyconnected to said driven element, a switching system mechanicallyoperated by said cam system, a capacitor and source of voltage, said camsystem operating said switching system and causing said synchro motor tobe a reversible motor in all but one position of said cam system, andcausing said synchro motor to be stationary at the remaining position ofsaid cam system.

2. A synchro system comprising, a voltage source, a capacitor, asynchro, a driven element, rotation reduction means connecting saidsynchro to said driven element, a cam system connected to said drivenelement, and switching apparatus operated by said cam system, wherebysaid capacitor is switched into the circuit between said voltage sourceand a stator winding of said synchro, said synchro thereby beingoperative as a reversible two phase motor in all but one position ofsaid cam system, and whereby said capacitor is switched out and voltagesfrom said source selected to lock said synchro are applied to its statorwindings at a predetermined remaining position of said cam system.

3. A synchro-automatioreset system comprising a receiver synchro, avoltag source, an impedance element, means connecting said impedanceelement with said synchro to said voltage source to operate said synchroas a reversible motor, a transformer energized from said source toprovide a locking voltage pattern, and switching means operated by saidsynchro at a predetermined position to disconnect said synchro from saidvoltage source and said impedance element and connect said synchro tosaid transformer locking voltage pattern whereby said synchro is lockedin said predetermined position.

4. A synchro automatic reset circuit for a synchronous data transmissionsystem comprising a receiver synchro, a voltage source, a lockingvoltage pattern derived from said source, a phase shifting impedance,switching means disconnecting said synchro from said data transmissionsystem and connecting said impedance with said synchro to said voltagesource for operation of said synchro as a reversible motor, and meansoperated by said synchro at its zero position to disconnect said synchrofrom said impedance and voltage source and connect said synchro to saidlocking voltage pattern whereby said synchro is locked at said zeroposition.

5. In a synchronous data transmission system, an automatically resetcircuit comprising, a receiver synchro, an auxiliary voltage supply, atransformer energized from said supply to provide a locking voltagepattern, means to operate said synchro as a reversible motor from saidvoltage supply, and switching means operated by said synchro at apredetermined position to disconnect said synchro from said voltagesupply and to apply said locking voltage pattern to said synchro to locksaid synchro in said position.

6. In a remote position indicating system in which the position of asynchronous transmitter is followed by the position of a synchronousreceiver, an automatic zero reset circuit comprising, an auxiliaryvoltage source, a transformer energized from said source to provide alocking voltage pattern, a normally de-energized magnetic switchconnecting said receiver to said transmitter, means energizing saidswitch to disconnect said receiver from said transmitter and to applyvoltages from said source to operate 5 said receiver as a reversiblemotor, and switching means operated by said receiver at its zeroposition to disconnect said receiver from said voltage source and toconnect said receiver to said locking voltage pattern whereby said. re-5 REFERENCES CITED The following references are of record in the file ofthis patent:

Number Number 6 UNITED STATES PATENTS Name Date Hewlett et a1 Apr. 9,1929 Read, Jr Mar. 12, 1946 FOREIGN PATENTS Country Date Germany Mar.13, 1930 Great Britain June 17, 1938

